[gedit] README: update dependencies

[Jeremy Bicha <jbicha src gnome org>]

commit 214c8ca735badec8396aeb0008170c4f9a123ca9
Author: Alexandre Franke <alexandre franke gmail com>
Date:   Mon Dec 3 20:14:42 2018 +0100

    README: update dependencies

 README.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/README.md b/README.md
index 51af1f219..49072ade2 100644
--- a/README.md
+++ b/README.md
@@ -59,15 +59,15 @@ Resources
 Installation
 ============
 
-gedit requires `GTK+ >= 3.22.0`, `GtkSourceView >= 3.22.0` and
+gedit requires `GTK+ >= 3.22.0`, `GtkSourceView >= 4.0.2` and
 `libpeas >= 1.14.1` libraries. It also has a run-time dependency on an
 icon theme for its icons. If gedit fails to display icons, installing
 GNOME's default adwaita-icon-theme is a simple way of providing them.
 
-`PyGObject 3.0.x` and `gobject-introspection 0.9.0` are required to enable
+`PyGObject 3.0.x` and `gobject-introspection 0.9.3` are required to enable
 python plugins support.
 
-`gspell >= 0.2.3` is required to enable the spell checking plugin.
+`gspell >= 0.2.5` is required to enable the spell checking plugin.
 
 Simple install procedure: